It is a common practice for physical therapists, chiropractors, and other medical practitioners to utilize various manual techniques to mobilize the joints of the spinal column, including the intervertebral joints, the synovial facet joints, the costovertebral joints, and the costotransverse joints. Such joint mobilization distends the joint capsule ligaments and reflexively relaxes the associated muscles. Synovial fluid, upon mobilization, will seep to areas of the articular cartilage surfaces to provide lubrication for the joints, decreasing pain and providing relief to the patient. The synovial fluid is pumped and shifted within the articular capsule of the joint by joint motions including flexion, extension, rotation, and a sliding action of the opposing joint surfaces relative to one another. Furthermore, the purpose of vertebral mobilization is to increase the intradiscal space between the vertebrae to allow for water diffusion and nutrition exchange within the vertebral segment (vertebrae-disc-vertebrae). When this happens, muscle spasms decrease, spinal mobility increases, and pain relief is achieved.
Physical therapists employ various hands-on techniques and forces to achieve the desired degree of joint mobilization. There are five grades of mobilization typically used:
Grades I and II are small amplitude movements performed at the beginning of range of motion at a given joint. The effect of these movements is to reduce pain by the aforementioned fluid movements. These movements are not sufficient to increase active range of motion.
Grade III is a large amplitude motion in the last half of range. This movement is sufficient to increase range of motion as well as decrease pain.
Grade IV is a small amplitude motion or a sustained pressure at the very end of range sufficient to stretch the joint at the point of resistance. The result is to increase range of motion to the limit of normal active range.
Grade V is a quick movement requiring a pressure fulcrum which produces a movement beyond the patient's active range of motion. It is sometimes called "popping" of the joints and is similar to the cracking of one's knuckles. In the spine, such hyperextension is useful to provide an immediate relief of pain and increase of normal active range.
One technique used by physical therapists to achieve joint mobilization is to have patients put two tennis balls in a sock and then knot them in the toe end. The patient is then instructed to place the thus contained tennis balls on the floor and move his or her back against them to achieve Grade III, IV or V mobilization.
Furthermore, soft tissue mobilization is a technique wherein the muscular tissues are physically moved relative to one another. The intent is to increase circulation of blood, stretch the muscle fibers and force fluids to exchange. Most importantly, soft tissue mobilization frees muscles from adherence to surrounding sheaths so that they can contract and relax freely again. A further intent of soft tissue mobilization is to decrease spasm of the muscles and to promote normal blood circulation.
Massage is a manual technique involving friction between the hand or a similar object and the skin. The skin may be moved against the underlying muscles in this action. The intent of massage is to increase surface circulation and cause a reflex generalized relaxation.
Joint mobilization, soft tissue mobilization, and massage can be accomplished by manual forces. In the case of the back, most of these techniques are difficult for patients to perform on themselves. Accordingly, there is a need for devices which can accomplish these techniques in an easy manner. Also, in order for a person to continuously apply a hands-on technique, a certain amount of strength and endurance is required. Thus, there is a need to develop therapeutic devices to supplement the hand.
When used as described, many prior devices are capable of accomplishing an adequate massage action as, for example, Layman U.S. Pat. No. 3,756,224, McCauley U.S. Pat. No. 4,347,838, Lohati et al. U.S. Pat. No. 4,577,625, Simmons U.S. Pat. No. 4,648,387, Gromala U.S. Pat. No. 3,616,794, Kim U.S. Pat. No. 4,712,539, Iwahashi U.S. Pat. No. 4,493,315 and Masuda U.S. Pat. No. Des. 269,375.
A common feature of most prior art massage devices is that they have complex contact surfaces, usually in the form of knobs and bumps, designed to produce multi-point stimulation of the skin. Most of these devices are made of hard, rigid materials, the purpose of which is to produce a sensory stimulation of the skin at many points simultaneously. Some of the therapeutic effects of massage may require a complex sensory input to the brain that appears to mask the perception of pain and allows muscle relaxation. None of these above referenced prior art devices are intended to produce appreciable joint mobilization.
Some prior art devices are designed primarily to produce soft tissue mobilization without affecting the underlying bones or joints. See for example, Kim U.S. Pat. No. 4,712,539 at column 1, lines 40-45. The device of this patent also is described as affecting so-called accupressure points in muscle tissues.
A massage device described in Iwahashi U.S. Pat. No. 4,493,315 is intended to provide therapeutic benefits by facilitating the circulation of blood via kneading actions (see column 1, lines 10-30). Other prior art devices use or incorporate wheel-like components to produce an effect on the muscles or the back to achieve relaxation. Examples are shown in the Gromala, Layman, Kim and Simmons patents discussed above. These devices can work on deeper muscle layers than can the purely massage-type devices, but they tend to have less aggressive contact surfaces. They employ smoothly rounded surfaces or resilient padding as in Iwashashi or tire-like contact surfaces as in Gromala. These devices may produce a degree of massage and soft tissue mobilization. However, if the goal is to produce significant mobilization of the joints, it is likely that bruising of the bones and other damage would occur if these devices were pressed hard enough to accomplish joint mobilization. For example, the Gromala patent, which is directed to muscle massage, cautions against using excessive force or use by a non-medically trained person (column 3, lines 1-5). Another example is the device of the Kim patent which is indicated to be specifically designed to avoid bone pressure (column 1, lines 40-45 and column 5, lines 1-5). The devices shown in the Iwashashi, Simmons, McCauley, Layman and Lohati patents were also designed to affect only muscles.
Further, most of the prior art devices are limited to application by another person and some suggest that significant medical training is necessary to avoid injuring the patient.